The Forestry Forum

General Forestry => Firewood and Wood Heating => Topic started by: 47sawdust on November 13, 2020, 03:54:11 PM

Title: wood stove water heater
Post by: 47sawdust on November 13, 2020, 03:54:11 PM
I've had this system in operation for close to 10 years. We use it to temper the water coming from our spring before it goes to the propane water heater. The water circulates from the stove to a 30 gallon stone lined tank.

Inside the soapstone stove is a small SS water jacket that I had made by a local machine shop.A White-Rogers aquastat turns on a Grundfoss circulator when the temp. reaches 140į. The piping is all 3/4'' copper. We are typically able to raise the water temperature by 60-70 degrees overnight with this system.

It has been trouble free (knock on wood), since I installed it.It's a great feeling to hear the circulator kick on and know we are getting a little extra out of our firewood.The stove is a Hearthstone Mansfield and I wouldn't have any other.

Chicken and dumplings in the dutch oven at the moment.


(https://forestryforum.com/gallery/albums/userpics/26307/20201113_151208.jpg?easyrotate_cache=1605298896)
 


Back of stove aquastat, pressure relief valve ,air eliminator and temp indicator
(https://forestryforum.com/gallery/albums/userpics/26307/20201113_150241.jpg?easyrotate_cache=1605300183)
 


Temp gauges in from spring, out to propane heater
(https://forestryforum.com/gallery/albums/userpics/26307/20201113_141117.jpg?easyrotate_cache=1605298973)
 



Tempering tank and water heater.
(https://forestryforum.com/gallery/albums/userpics/26307/20201113_141149.jpg?easyrotate_cache=1605300228)
 
(https://forestryforum.com/gallery/albums/userpics/26307/20201113_141224_28129.jpg?easyrotate_cache=1605300249)
 

There are only 20 valves in my basement. My big accomplishment this year was labeling them all to give my wife a little piece of mind. ;D
Title: Re: wood stove water heater
Post by: doc henderson on November 13, 2020, 04:35:16 PM
any heat loss from the piping or the tank will still heat your home, and water from a bath or shower will add heat and humidity.  in the winter, if someone takes a bath at our house, the water stays in the tub for a few hours or overnight to release the heat and some humidity.  If really cold we do not use the exhaust fan when taking a shower.  great system, and not seen from the font of the stove, also a wife pleaser.   8) 8) 8)
Title: Re: wood stove water heater
Post by: GRANITEstateMP on November 13, 2020, 05:33:00 PM
Mick, I really like the labels! I should have my plumbing buddy come over and re-educate me on half of my valves!
Title: Re: wood stove water heater
Post by: Bruno of NH on November 13, 2020, 05:42:46 PM
Very nice Mick
I was thinking in my head the other night about doing something similar. 
Title: Re: wood stove water heater
Post by: Nathan4104 on November 13, 2020, 05:44:36 PM
Nice set-up and thatís a beautiful stove!!
We ran a water jacket in our Elmira Fireview cook stove for a few years, to heat our basement slab.  
One issue we had was when the power went out and the circulator stopped.... so I had it hooked to an inverter on a deep cycle battery, which had a battery maintainer on it to keep it charged.  However.... one day someone took the battery for something else cause heating season was about done.  Lo and behold the power went out that day.... apparently the pressure relief worked just as it should have.  But the water pump does not so eventually the system runs out of water... 
One other issue was the build up of creosote on the water jacket itself. With That cool water coming back in, the jacket never warms up and the creosote would form.  Iíd have to scrape it off with a paint scraper every now and then.    And that was burning seasoned, good dry wood.  
I removed the jacket for those reasons. Iím curious if youíve had any similar experiences?! 
Title: Re: wood stove water heater
Post by: 47sawdust on November 13, 2020, 06:50:00 PM
GranitestateMP- After I printed the info. on the labels I had them all laminated. No way to erase my mistakes.

Nathan, I had the same set up as you for power outage, it could be a wild scramble to get things changed around. I installed a seamless standby generator and now I have more peace of mind.
The creosote is not too bad , but your point is well taken.We do burn very dry wood and try to run the stove on the hot side. the soapstone provides a very even heat
Title: Re: wood stove water heater
Post by: mudfarmer on November 16, 2020, 06:52:30 PM
That is a very nice and slick setup, thank you for sharing! Is the small (4"?) stovepipe looking piece behind the wood stove a fresh air intake that goes through the floor to basement or just down towards the floor to draw in colder air?

We have a Fisher Honey Bear (Golden Bear maybe? can't remember) that is on a pedestal, it is meant to draw cold air through the floor of a mobile home but I have not set it up that way yet..
Title: Re: wood stove water heater
Post by: mike_belben on November 16, 2020, 09:45:01 PM
Dont put it off too long.  Big performance improvement when you introduce combustion air intentionally where it wont blow on anyone, instead of through every crack in the dwelling.  
Title: Re: wood stove water heater
Post by: 47sawdust on November 17, 2020, 12:26:25 AM
mudfarmer,
Yes, the black pipe is an outside air intake.It makes all the difference in the stoves performance.The glass on the door only needs cleaning once a season.Before installing the outside air intake the glass would need cleaning once a week.
It pulls in outside air ,not basement air.
I have an outside air intake on my wood stove in the garage as well.I'm a believer.
Title: Re: wood stove water heater
Post by: mudfarmer on November 17, 2020, 06:58:17 AM
wife: "Why are you cutting a big hole in the floor??" :snowball:
me: "I thought it was a good idea and so did some guys on the internet" 8)


Thanks! I wish the Fisher had a built in water jacket like the little bitty top loader cook stove we have, what a nice feature. Will consider setting something up like 47sawdust's rig, it is very nice and would be great to take the edge off before it hits the propane heater.
Title: Re: wood stove water heater
Post by: mike_belben on November 17, 2020, 07:41:14 AM
Pay attention to the stove after its been established a while, and have her open the exterior door of the house while you watch the flame come back to life. 


  However much air is going up the flue needs to be replaced or the house interior goes under vacuum. New tight houses can hardly run a stove without inlet venting.  
Title: Re: wood stove water heater
Post by: 69bronco on November 19, 2020, 05:36:59 AM
mudfarmer,
Yes, the black pipe is an outside air intake.It makes all the difference in the stoves performance.The glass on the door only needs cleaning once a season.Before installing the outside air intake the glass would need cleaning once a week.
It pulls in outside air ,not basement air.
I have an outside air intake on my wood stove in the garage as well.I'm a believer.
Is there an intake on your stove that is ducted? Thats a great idea for newer/tighter homes. Have never seen a stove with a fresh air specific intake. Very nice!
Title: Re: wood stove water heater
Post by: 47sawdust on November 19, 2020, 07:01:11 AM
Both stoves, Hearthstone Mansfield and Waterford Trinity have provisions for outside air intake.
The Waterford stove is a very rare bird and no longer available.
Title: Re: wood stove water heater
Post by: doc henderson on November 19, 2020, 07:49:17 AM
we did this with our earth stoves in the past
Title: Re: wood stove water heater
Post by: mike_belben on November 19, 2020, 08:05:12 AM
I bored a 3" holesaw into the side of the one in my shack, welded in a stub of pipe and drilled a vertical hole thru both walls of the pipe.  Then fitted the holesaw knockout circle into a throttle blade to go in the stub.  Then basically inserted a big barn nail through the hole, pushing a spring ontop, then a washer, compressed it, welded it and bent a dogleg for a handle. This way it stays set by spring friction.  Then welded the circle to the shaft to make a choke valve. No it doesnt need a perfect seal.  



Next, drilled a 3" hole through the floor in the corner behind the stove, rolled up a clump of chicken wire for a critter screen and stuck it inside a flexible aluminum appliance duct that goes down through the floor and connects to the intake "carburetor" id already described.  



At startup, i hit the stack with a bottle torch to preheat the air in the pipe and get it drafting in the right direction.  Keep the outside air shutoff so it pulls any smoke up the pipe and not leak into the house.  


Once your interior air is up to temp and heated you want it to stay indoors, so close the interior damper [the ash drawer in my case] and open up the exterior inlet air. That way you got full blown combustion air without drawing a whole house vacuum that pulls cold air into every single crack and creates drafty currents, cold spots, dust streaks etc etc. And you arent exhausting the air you just worked to heat, by letting your flame consume and exhaust it.  


It is a huge design flaw not having a controlled exterior cold air source for such a major exhausting appliance.  Imagine the CFM of a sawdust blower with an 8" pipe run on a low rpm whisper mode.  Thats how much air your stove moves out, and wants brought in.  
Title: Re: wood stove water heater
Post by: mike_belben on November 19, 2020, 09:05:48 AM


(https://forestryforum.com/gallery/albums/userpics/43722/1129181056a.jpg?easyrotate_cache=1605794332)



(https://forestryforum.com/gallery/albums/userpics/43722/1129181056.jpg?easyrotate_cache=1605794321)


Forgot that i crimped the inside of the tube into a convergent nozzle to help increase velocity, dispersal and penetration into the firebox and also as a check valve to make it harder for smoke and flame to escape out the tube.  I do wish i put it lower but it has not been any issue.  


I also built a baffle plate with a sliding window up on top to block the flame from going straight to the stack pipe and eating it up.  Flames are forced to go up against all walls pretty equally to get around the baffle.  That dramatically increased temps all over as has always been my experience.  I mount my stack damper as far upstream as i can also.  Keep as much flame indoors as you possibly can.

Title: Re: wood stove water heater
Post by: Technoid on March 03, 2021, 07:41:02 PM
My system is a gravity feed. I have a Harman stove with a stainless steel horse shoe loop 3/4 pipe inside the firebox. in series with an overhead forced air heater. Then down to the domestic 30 gallon hot water heater. There is an agastat on the over head heater set to 180 deg for the fan. It prevents over heating of the loop. Then back to the stove. There is also a safety pressure valve in the circuit. Also an expansion tank. The oil burner never runs with the stove burning. Recharge after a shower only takes 1/2.